<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>透明度opacity</title>
    <style>
        body {
            background-color: #dc4242;
        }
        img {
            opacity: 0.7;
        }
    </style>

</head>
<body>
<img src="images/abcd.jpg" alt="">
</body>
</html>